Stabilizing wool



'as formaldehyde.

Patented Feb. 26, 1946 STABILIZING WOOL Edward C. Pfeflcr, In, and Walter Kitai, Troy, N. Y., assignors to Cluett Peabody & 00., Inc., Troy, N. Y.. a corporation of New York No Drawing. Application November 3, 1944, Serial No. 561,840

'18 Claims. (CL 8-1155) This invention relates to woolen textile materials and has for its object the provision of a novel treatment of fabrics composed of or containing wool to eliminate their tendency to shrink on washing.

Fabrics made of or containing wool shrink excessively when subjected to ordinary washing operations and considerable effort has been expended on the development of processes to reduce or prevent the shrinking of woolen fabrics during washing, but none of the methods heretofore proposed has been entirely successful, or even sufficiently successful and practicable to'warrant large scale commercial use.

We are cognizant of the methods and processes which have been previously proposed for shrink-proofing wool, One group of these processes involves treating wool fiber or woolen fabrics with halogens in the form of chlorine or bromine gas, or with solutions of hypochlorous acid, sodium hypochlorite, organic hypochlorites, or sulfuryl chloride, alone or in the presence of acidifying agents and in some cases even containing added reducing organic substances such It is presumably the object of these processes either to destroy thescales of the wool fibres or to gelatinize them and alter their structure in such manner that mechanical felting is thereby prevented. We have tested such processes but find that they tend to damage the wool fibers by making them harsh and brittle, reducing the tensile strength and resistance to wear of woolen fabrics, and producing an undesirable hand, when an adequate degree of shrinkproofing is obtained.

Another group of processes suggests the treatment of wool with alkalies, such as sodium or potassium hydroxide or organic bases, under such conditions that only the surface structure of the wool fibers is attacked and altered, thereby to eliminate mechanical felting. For example, the wool or woolen fabric is treated with potassium hydroxide in organic solvents such as methanol, ethanol or aromatic alcohols in order to prevent damage to the medulla of the wool fibers and restrict action to the epidermis scale structure. High concentrations of alkalies in aqueous solution have been suggested for the same effect. We find that this type of treatment likewise tends to damage the fiber and impart an undesirable harsh hand to the fabric when an adequate defind that when a suflici'ent gree of shrink-proofing is obtained, even though i.

the alkali be applied to the wool in alcoholic solution.

It has also been proposed to treat woolen fabfabric is undesirably harsh,

.aqueous solution, which is rics with synthetic resin-forming compounds to reduce the shrinking tendency, for instance, shrink-proofing woolen fabrics by treatment with alkylated methylolm'elamine resin-forming compounds. In such treatments the wool fibers are impregnated aqueous solution and the resin formed in situ within the fibers by a heat treatment. It is presumably the object of this latter type of process to decrease the water-sensitivity of the wool fibers and eliminate in contact with water and soap solutions. We quantity of resin is formed within the fibers to produce any adequate degree of shrink-proofing, the hand of the woolen shrink-proofing effect is not to washing.

Another shrink-proofing process for wool pro- I poses treating woolen fabrics first with a resist, in the form of a resin-forming chemical in cured in-situ in the fibers to protect them from damage with an anti-felting agent such as chlorine solution. We find that the resin resist interferes with the action of the halogen and an adequate degree of shrink-proofing is not produced.

It has also been suggested to shrink-proof wool by treatment with enzymes such as papain, or by the use of reducing agents such as sodium hydrogen sulphide, mercaptan or thlo-glycollic acid, but such treatments either are not effective or are impractical because of highly disagreeable odors and in some cases the expense and unavailability of the reagents. I

We have not found any of the methods and processes proposed for-shrink-prooflng wool in the literature or in prior patent art to be sufficiently effective and practicable. In all prior treatments, if a satisfactory degree of shrinkproofing is obtained there is very serious fiber damage with consequent reduction in tensile strength and in wearability, and an undesirable stiffening of the fabric is produced. If the processes are so controlled that damage to the fiber and the hand of the fabric are not produced, the shrink-proofing effect is not satisfactory and is not permanent. We believe that the previously proposed methods of shrink-proofing wool have not been successful because no prior proposed process alone recognizes that atleast two factors are responsible for the shrinkage of wool, both of with a resin-forming chemical in their swelling and softening and in any case the entirely permanent and then water. the term intended to be inclusive of true solution when the sufilcient alon to destroy the epidermis or surface scale structure of the fibers, which i accomplished at least to a considerable degree by treatment with chlorine or chlorinating agents, or by treatment with alkalies such as potassium hydroxide. Moreover, it is not alone sufiicient in shrink-proofing wool to treat the woolen fabric and fibers with a synthetic resin or the like to increase the resistance of the fibers to water and decrease the softening and swelling of the fibers with water. The two factors responsible for the shrinkage of woolen fabrics must both be controlled or eliminated in order to produce an entirely satisfactory result. These two factors are:

1. The peculiar physical constitution of the wool fibers comprising an epidermis consisting of sur- 'face scales which causes mechanical shrinkage or felting. l

2. The sensitivity of the wool fiber to water with a consequent high degree of swelling with water,

which magnifies the mechanical felting and.

causes shrinkage also by its own efiect due to increase and decrease of the fibers in diameter during alternate wetting and drying cycles.

We have found that the tendency of woolen fabrics and fabrics containing wool to shrink excessively on washing can be eliminated by treatment with a process such that both of the above factors causing shrinking of woolen fabrics are controlled. In our process the woolen fabrics are first treated with an alcoholic caustic solution but in such manner that no intrinsic damage to the fibers occurs and there is no harmful efiect on the hand of the fabric. Th s treatment alone is not sufilcient to give any effective degree of shrinkage control. but in combination with the second step of our process a very eiIective degree of shrinkage control is obtained. In the second step of our process the woolen fabric, which has already been treated with th alkalisolution. is impregnated with a synthetic resin-forming chemical in water solution or dispersion and the fabric is then cured to fo m and insolubilize the resin in the fibers. While most of the resin-forming chemicals found useful are dispersed when added to dispersion as here employed, is

resin-forming chemical employed does actually dissolve in water. In this combined process neither treatment when used alone produces any effective degree of shrinkage control. but the two treatments used together, with the proper technique and applied successively, produce a very adequate and effective degree of-shrink-proofing of woolen fabrics. The treated fabrics have a greatly reduced tendency to felt and shrink, as shown by the fact that woolen fabrics so treated have as little as 2% residual shrinkage'and no progressive shrinkage, that is, the tendency to felt has been eliminated and at the same time the resistance of the fibers to softening and swelling with water has been greatly improved. The

result produced by our combined process can not be ascribed to the simple addition of the results produced by two separate processes, since neither step as practiced in our process has any appreciable degree of effectiveness when used alone. The combined process however, controls both of the factors which cause shrinkage of woolen fabrics, without damage to the hand or strength of the fabrics.

The first step of our shrink-proofing process for wool consists of treating the woolen fabric by immersing it in an alcoholic caustic solution under controlled conditions in reference to concentra tion of caustic, temperature of solution and time of immersion such that only a partial reduction of felting is obtained. without any adequate degree of shrink-proofing and also without any stifiening or tendering of the fabric. The following table shows the effects of various treatments after one and five laundry washes, and in reference to hand and strength of the treated samples.

In the above table, treatments with 7.5% KOH inalcohol at 70 F. to F. for 5 minutes represent proper practice of the first step of our process. It may be noted that the fabric has not been made adequately shrink-proof by any means in this case. It may also be noted that by treatment with 7.5% KOH in alcohol at to F. for 5 minutes thefabric is made resistant to felting and has low shrinkage, but the hand and strength of the fabric have been damaged. Our practiceis not represented in this case.

Alternate satisfactory treatments can be produced by logical variations of time, temperature and concentration as shown by the treatment with 4% KOI-I in alcohol at 70 F. for 10 minutes and the treatment with 7.5% KOH in alcoholat 100 F. for 1 minute, but the conditions must be such that only a partial shrink-proofing is obtained without damage to the hand or strength of the fabric.

After the fabric has been immersed in the alcoholic caustic solution for the proper time it is run through squeeze rolls to remove as much solution as possible and is immediately neutralized in 2% sulfuric acid solution, or other weak acid solution, at normal temperatures. The

-fabric is then thoroughly rinsed, dried and is shrinkage evaluation.

the fibers. In the practice of our process it is not necessary and is not desirable to form a high concentration of resin in the fibers, whereas it would be necessary to form a relatively high percentage of resin in the fibers were it attempted to shrink-proof wool by resin treatments alone and even then satisfactory results are not obtained. By the use of a relatively low quantity of resin-forming material, stifiening of the fabric is avoided. The following table shows the' effects on the shrinkage, hand and strength of a woolen fabric given various resin treatments, with and without our preliminary alcoholic caustic treatment as described previously. The resin percentages shown are the percent resin. solids formed in the fabric based on the dry fabric weight. In all cases a cure, or heat-treatment at 290 F. for 8 minutes was given the impregnated fabric. to insolubilize the resin. Aerotex M-3 is a water-soluble methylated methylolmelamine pre-condensate' and the acid catalyst used with this resin-forming chemical was diammonium hydrogen phosphate at .3% in the impregnating solution. Beckamine 19-424 is a water-dispersible low molecular weight ureaformaldehyde pre-condensate and was catalyzed by .3% oxalic acid in the impregnating solution. Rhonite 313 is a water-soluble alkylated ureaformaldehyde pre-condensate and was catalyzed by .3% ammonium chlor' de in the impregnating solution.

The pre-treatment, wlere indicated, consisted of a 5 minute immersion in 7.5% potassium hydroxide in ethyl alcohol (proprietary solvent) at '10 F., the woolen fab c then being squeezed, neutralized in 2% sulfuric acid,-rinsed and dried. The fabric was not permitted to take any shrinkage loss during the treatments prior to washing for The shrinkage results show shrinkage in the warp direction only for simplicity.

sates.

yard shrinkage after 15 washes. Also, this result is obtained without deleterious effects'on the hand and strength of the fabric. These resultsare clearly shown in the case of the Aerotex M treatments. In commercial practice the first wash shrinkage shown in the above data for our two-step treatment can be allowed to occur as a process, or working loss. Thus, in the case'of the alcoholic caustic and 3% "Aerotex M3" pi'ocess shown above, thetreated fabric would then shrink 2% in 15 laundry washes.

In the practice of our shrink-proofing process, the woolen fabric, after pre-treatment with 'alcoholic caustic solution as described, and after neutralizing, rinsing and drying, is-impregnated with the solution of resin-forming chemical by running it through a padder, using a tight squeeze in order to obtain a solution pick-up of around 100% based on the dry fabric weight. The impregnated falbric is then dried and baked at temperatures between 212 F. and 350 F. for periods of between 2 minutes and minutes, the baking time normally being inversely proportional to the baking temperature. The function of this curing operation is to condense and insolubilize the resin within the fibers. After curing, the fabric is soaped, preferably under low tension, and is then dried without tension.

We believe that any resin-forming chemical,

soluble in water or dispersible in water in a particle size small enough to penetrate the swollen fibers and which will condense. to the insoluble state on the application of heat, can be usedsuccessfully in our process. However, we prefer the water-soluble or water-dispersible amino-aldehyde resin-forming chemicals. or pro-conden- This includes the monomeric reaction products or the low molecular weight intermediate reaction products of formaldehyde with urea or melamine and the alkylated reaction I Table 2 Warp shrinkage in inches per yard Treated Pro-treatment Resin treatment lwash washes i Hand Strength 10. 2 15.7 20.1 Normal. Normal. d0 7.0 9.8 14.5 0. K..-. O. K.

127 "Aerotex M- 2. 5 4.6 10.2 Heavy.- Slightly reduced. 3% Aerotex M-B- 3.2 5.9 14.0 0. K.- 0. K. -do 1.5 2.0 2.2 O. K-.-. O. K.

12% Beckamine P424". l. 7 5.0 12.0 Stiff"-.- Reduced. 6% Beckamine 1 -424.-. 3. 2 9.0 15.8 0. K.... O. K.

a e 3.1. 12 ,f oni e eavy y u 5.) 3% Rhonite 31a as 11.1 16.4 0. K 0. K. 5'7.5% KOH-E. A. at F "do .7 1.8 2. 5 0. K O. K.

It may be noted from the above data that high concentrations of resin in the fibers, in the attempts to shrink-proof wool with resins without pro-treatment, were not very concentrations of resin in the fibers were not effective at all withoutpre-treatment, but were very efiective in shrinkprqofing the woolen fabric pre-treated with our alcoholic caustic treatment. The important fact presented in this table, however, is the un pected result that an alcoholic caustic treatment (which is ineffective alone in preventing shrinkage and allows 14.5 inches per yard shrinkage after 15 washes) combined with a resin treatment (which is also ineffective alone in preventing shrinkage and allows 14.0 inches per yard shrinkage after 15 washes) produces a treated woolen fabric with only 2.2 inches per effective. The lower products thereof. cessful results with resin-forming chemicals which, after condensation, form urea-formaldehyde, melamine-formaldehyde, alkylated ureaformaldehyde and alkylated melamine-formaldehyde resins. It is necessary to use acid catalysts with such compounds in order to form the resins within the fibers in a reasonable curing time and such catalysts as diammonium hydrogen phosphate, oxalic acid, acetic acid, zinc chloride, phosphoric acid, ammonium chloride, and others are satisfactory for the purpose.

We prefer to cure the impregnated fabric at a temperature of around 290 F. for a period of about8 minutes. Much lower temperatures increase the time required to too greats. degree,

Specifically, we obtain suc-.

while much higher temperatures damage the wool fibers Exmul A plain weave 100% all woolen fabric, weighing 5.4 ounces per square yard, having a count of s di-ammonium hydrogen ing 3% total solids oi Aerotex M-3" (supplied by American Cyanamid Co.) and 0.1 Accelerator 187" (same supplier) as catalyst, the effective constituents of "Accelerator 187" being phosphate. The fabric then passed through squeeze rolls to obtain fits / a solution pick-up of 100%. The fabric was then tentered, dried and cured for eight minutes at F. The treated fabric was found to be per- 42 x 24 and consisting of 25/1 worsted yarn in manently resistant to shrinkage on continued the warp and 6/1 worsted yarn in the filling was immersed for llveminutes in an alcoholic solution at 70 F. containing 7.5% potassium hydroxide by weight. This alkali solution was Prepared by dissolving technical potassium hydroxide in proprietary ethyl alcohol and the impregnating solution was kept in a water bath at a constant temperature. The sample at the end of five minutes was passed through rubber squeeze rolls to remove surplus alkali and the solution remain- 2o ing in the fabric was neutralized by immersion in a 2% sulfuric acid solution. The fabric was then rinsed several times in water to remove the acid,

'after which the fabric was tentered and dried.

The dried fabric was then passed through a resin solution which contained 6% total solids of Beckamine P424 (supplied by Reichhold- Chemicals, Inc.) and 0.3% of oxalic acid. The surplus resin solution was then removed-by a tight squeeze to obtain solution pick-up of about so 80%, and the fabric dried on a tenter frame and cured for eight minutes at 290 F.

This treatment imparted a slightly stiffened hand to the fabric, but improved the abrasion resistance considerably without damaging tensile strength and crease resistance. In commercial practice the wool can be softened chemically by softeners, preferably of the cation-active type, or mechanically by machines which exert a softening action on the' wet fabric, as for example a dolly washer. The treated sample was permanently resistant to felting as shown in the following table. Standard wash results were obtained by washing the treated and the untreated fabrics for fifteen minutes in a mild soap solution 45 at 100 F. followed by two warm water rinses of 5 minutes and 10 minutes (making a total time of minutes). The shrinkage figures are given only for the warp direction since the shrinkage in the filling direction is usually much smaller.

Total percent shrinkage-warp direction laundering. The hand, crease-resistance and tensile strength were not impaired. Abrasion resistance was superior to that of the control.

on washing, measured in the warp direction, of the treated and untreated fabric.

Total percent shrinkage-warp direction As in Example 1, most of the remaining 5.6%

kage can be taken as process loss in commercial procedure resulting in a fabric stable to within'a 2% tolerance.

Exsrrru 3 A 100% woolen twill fabric, weighing 7.5 ounces per square yard, having a count of 50 x 42 and consisting of 13/1 worsted yarn in both the warp and'fllling was immersed for one minute in a 7.5% solution of potassium hydroxide in ethyl alcohol at 100 F. This solution was made up as explained in Example 1. The l'abl'ic was then passed through rubber squeeze rolls, neutralized 40 in dilute sulfuric acid, tentered and dried. The

dried fabric was then impregnated with an aqueous solution of 3% total solids of Rhonite 313" (supplied by Rohm 8r Haas Co.) and 0.2 grams of ammonium chloride. After thorough wetting, the fabric was again passed through a mangle to obtain about 100% resin pick-up, then dried and cured for eight minutes at 290 F.

The treatment did not harm the tensile strength or crease-resistance and improved the abrasion resistance greatly, but somewhat stifisued the hand. Wool thus treated can be softened easily by mechanical action. The treated Nmofwgsheg and untreated fabrics were washed as described in previous examples and the shrinkage deter- 1 a a 4 s 0 15 mined in the warp direction through fifteen washes. The results are shown in the following Untrgzed 19.: eg 4 1.; egg 5 6.1 1 table:

Total percent shrinkage-war direction We find that by proper mechanical handling The plain weave mine described in Example 1 was immersed for five minutes in a 7.5% solution ized in 2% sulfuric acid solution. After thorough rinsing in water, the woolen fabric was tentered and dried. The dried fabric was then well wetted out in an aqueous resin solution contain- 75 most of the remaining 6% shrinkage could be washes eliminated as process loss in commercial pro- 1 2 4, 5 m 15 cedure thus resulting in a fabric stable to within 8.2% oleran e. Untreated 15.3 12.3 20.3 21.4 23.3 23.9 31.

Exams: 2 Treated-.. o o .s .s 1.1 1.4 2.

Exmss: 4

A plain weave 100% all woolen fabric weighing 6.2 ounces per square yard, having a count of 40 x 34 and onsisting of 13/1 worsted yarn in the warp and 12/1 worsted yarn in the filling was immersed for five minutes in an alcoholic solution at 7.5% sodium hydroxide at a constant temperature of F. The surplus alkali was The following table shows the percent shrinkage asosner removed by passing through a tight squeeze roll and the remaining alkali neutralized in dilute sulfuric acid. The sample was thoroughly rinsed and then dried on a tenter frame. The dried fabric was then immersed in an aqueous solution of 6% total solids of Beckamine P424 and 0.3% oxalic acid. After removing surplus resin by passing the fabric through squeeze rolls,

sible variations in the treatment with holic caustic solution. In the treatment of any given material the upper permissive limit of the range of treatment with the caustic solution may be determined by comparing the tensile strength of samples of the treated and untreated material,

itwas dried on the frame and then cured for m eight minutes at 290 F.

The tensile strength and crease-resistance of the fabric were unimpaired; the abrasion resistance greatly improved, but the hand somewhat stiffened. As mentioned in previous examples it is possible to soften the hand of the fabric by mechanical or chemical action.

The'treated and untreated fabrics were given fifteen standard washes as described before. The 1 wash results show that the treatment eliminated most of the progressive shrinkage.

Total percent shrinkage-warp direction No. of washes Untreated 28. 6 Treated. 2. 8

Part of the remaining 4.7% shrinkage can be plus acid washed out in three water rinses, and.v

the sample tentered and dried. After thorough drying, the fabric was immersed in a solution of 3% total solids of "Aerotex M-i. and 0.1% of Accelerator 187" dissolved in water, and the excess. solution removed by passing the fabric through tight squeeze rolls. The sample was then dried on the tenter frame and cured for eight minutes at 290 F.

The color, crease-resistance, tensile strength and hand of the fabric was unchanged by this treatment; the abrasion resistance was improved.

since the effect on the strength of the fabric furnishes a sharp definition of the upper limit of the range of alkali treatment. For example woolen fabric treated with a 7.5% alcoholic alkali solution for five minutes at the temperatures of 70, 80 and 90 F., respectively, and tested for tensile strength, showed the, following results as compared with the untreated material:

Csustio treatment i Wm; am. Pounds None 26 22 113 is evident that the treatmentat 90 r. represents an over-treatment, resulting in a great reduction of tensile strength, that is to say approximately 67% in the warp direction and.45%

in the ments at 70 and80.represent satisfactory practice, there being no appreciable reduction in tensile strength by reason of the treatment at 70',

while the reduction in strength through -treat-. mentat 80 was less than 20%, both in the warp and filling direction. This amount of decrease in strength is permissible, and thus the upper limit of alcohol caustic treatment may be determinedas that at which the resultant decrease in strength exceeds 20%.

The upper limit of the range of alcohol caustic treatment may also be determined in any given instance by testing for weight loss. This test depends upon the fact that damaged wool is more soluble in an aqueous solution of caustic alkalithan undamaged wool. For instance woolen fabric treated as above-described with alcoholic caustic solution at 70 F., 80 F., and 90 R, respectively, was dried and then digested for one hour at C. in OlN sodium lwdroxide. A sample of the untreated fabric was likewise digestedin the sodium hydroxide solution, and the following table indicates the loss in weight of these four samples as a result of this treatment.

The wash results of fifteen consecutive washes of the treated samples and the control fabric are reported in the following table:

Total percent shrinkage-warp direction No. of'washes Untreated Treated The results indicate that the above described double treatment eliminated most of the felting action without damaging any of the desirable qualities of the fabric. Here, as in the first example, the shrinkage left in the fabric can be taken care of by proper commercial handling.

Caustic treatment weight Per cent None. 16. 7 70 F l0. 7 F. 16. 7 F. 24. 3

In this instance the treatment at 90 F. shows a very marked reduction in weight, a reduction in fact 50% greater than that of the untreated or properly treated fabrics.v Thus by this test for weight loss, the upper limit of permissive treatment with the alcohol caustic solution may readily be ascertained.

Another way of determining the upper range I of alcohol caustic treatment is by observing the resulting stiffening of the fabric. Samples of woolen fabric treated with the' alcohol caustic solution at 70 and 80 have a soft, normal hand The above specific examples represent permis- 75 or feel, whereas fabric treated at 00 F. is very the alcofilling direction. .On the other hand treatsubstantially stiffened. Thus the upper limit of treatment with the alcohol caustic solution may readily be determined by the point at which the fabric begins to show appreciable stiffness.

As respects the resin treatment, no satisfactory shrink-proofing of woolen fabric by treatment" with resin alone, can be obtained except by substantially more than 6% by weight of r based on the weight of fabric.

on the other hand, when the resin treatment follows the treatment with alcohol caustic solution, it is possible to obtain very satisfactory results with less than 6% resin. It thus appears that 6% resin, based on the weight of the fabric, is the upper limit of the resin which should be employed in this dual treatment.

Our process is not limited to application to pure wool fabrics, so that fabrics made of blends of wool with cotton, wool with rayon and wool with acetate or other fibers can be satisfactorily treated. Neither step of our process is suillciently drastic to harm the physical properties of the fabrics, and in addition to the unimpaired hand and strength of the treated fabrics, the natural crush resistance of woolen fabrics is retained.

We claim: v 1. That method of stabilizing wool with respect to laundry shrinkage, which comprises as steps first treating the wool with an alcoholic caustic solution thereby partially to reduce the felting.

qualit of the wool but stopping the treatment when the wool has lost approximately 16.7% of its initial tensile strength and then with a synthetic resin-forming material in water dispersion containing not more than 6% solids and curin said resin-forming material to insolubiiize it, the successive treatments with caustic and resinforming material being each insufiicient in itself to produce any effective stabilization.

2. The methodof stabilizing wool with respect to laundry shrinkage, which comprises as steps wetting the wool with an alcoholic solution 01 a caustic alkali in from 4% to 7.5% strength at a temperature between 70 and 100 F. and for a period of timebetween one and ten minutes, the time and temperature varying inversely, stopping the treatment before the wool has lost more than 20% of its initial tensile strength and before effective shrinkproofing of the wool, removing excess solution, neutralizing the alkali with acid, rinsing and drying the wool, then impregnating it with an aqueous solution of a resin-forming material, and drying and heating the wool to condense and insolubiiize the resin-forming material, the amount of resin-forming material in water solution not substantially exceeding 6% total solids, which is insumcient, except when preceded by a caustic treatment, to produce effective stabilization.

3. The method of stabilizing wool in respect to laundry shrinkage, which comprises as steps first subjecting the wool to the action of an alcoholic caustic solution, stopping the treatment before the wool has lost more than 20% of its initial tensile strength,-and thereafter treating the wool with methylated methylol melamine precondensate and subjecting the wool to a temperature suflicient to complete the curing of said precondensate, the amount of such precondensate so applied not substantially exceeding 6% upon the weight of the textile material.

4. That method of stabilizing wool in respect to laundry shrinkage, which comprises as steps first subjecting the wool to the action of caustic alkali in alcoholic solution, the treatment ein stopped before the wool has lost more than 20% of its initial tensile strength, and thereafter treating the wool with an aminoaldehyde resin-forming material in water dispersion containing not more than 6% total solids, together with an acid catalyst, and thereafter subjecting the wool-to it ouring treatment to complete the polymerization of the resin-forming material.

5. That method of stabilizing wool with respect to laundry shrinkage, which comprises as steps first treating thewool with an alcoholic solution of a caustic alkali containing at least 4.0% caustic by weight, and at a'temperature not substantially exceeding F. and for a period between five and ten'minutes varying inversely with the strength of caustic, thereby partially to reduce the felting quality of the wool, the treatment being stopped before the wool has lost more than 20% of its initial tensile strength, neutralizing the alkali, then wetting the wool with a dispersion of an amino-aldehyde resin-forming substance, the dispersion containing not more than 6% total solids and an acid catalyst, and curing the wool at a temperature of approximately 290 F. for a eight minutes. 6. That method of stabilizing wool with respect to laundry shrinkage which comprises as steps first treating the wool with an alcoholic solution containing from 4.0 to 7.5% caustic alkali by weight, neutralizing the wool, then wetting the wool with a dispersion of an amino-aldehyde resin-forming substance, the dispersion containing from 3 to 6% total solids and an acid catalyst, and curing the wool at a temperature of approximately 290 F. thereby to complete the polymerization of the resin-forming substance.

"I. That method of stabilizing wool with respect to laundr shrinkage, which comprises as steps wetting the wool with. an alcoholic solution containing from 4.0 to 7.5% caustic alkali by weight thereby partially to reduce the felting quality of the wool, but stopp the treatment before the wool has been damaged to an extent such, that if digested with an aqueous caustic solution, it will lose more than 16.7% of its initial tensile strength, removing excess solution, neutralizing the alkali with acid, rinsing and drying the wool and then impregnating the wool with an aqueous dispersion of an amino-aldehyde precondensate, the dispersion containing from 3 to 6% total solids and an acid catalyst, and curing the wool at a temperature of approximately 290 F. thereby completing the polymerization of the pre-condensate.

8. That method of stabilizing wool with respect to laundry shrinkage, which comprises as steps first treating the wool with an alcoholic solution of a caustic alkali of between 4% and 7.5% strength and ata temperature between 70 and F., the temperature varying inversely with caustic strength thereby partially to reduce the felting quality of the wool, but stoppin the treatment before the woolhas lost more than 20% of its initial tensile strength, neutralizing the wool with acid and washing it to remove the acid,

. and wetting the wool with a water dispersion of a low molecular weight, urea-formaldehyde precondensate, the dispersion containing not more than 6% total solids and approximately 0.3% oxalic acid as a catalyst, and thereafter curing the wool at a temperature of approximately 290 F. for a period of approximately eight minutes.

9. 'That method of stabilizing wool with respect to laundry shrinkage, which comprises as steps period of approximately first treating the wool with an alcoholic solution or a caustic alkali of from 4% to 7.5% concentration and for a period or time varying between one and ten minutes, thereby partially to reduce the felting quality of the wool, ,but stopping the treatment before the wool has lost more than 20% of its initial tensile strength, neutralizing the wool with acid and washing it to remove the acid, wetting the wool with a water dispersion of an alkylated urea-formaldehyde pre-condensate, the dispersion containing approximately 3% total solids and a fractional percentage of ammonium chloride as a catalyst and thereafter curing the wool at a temperature of approximately 290 F. thereby completing the polymerization of the pre-' condensate. 10. That method of stabilizing wool with respect to laundry shrinkage, which comprises as steps first treating the wool with an alcoholic solution of a caustic alkali of from 4% to 7.5% concentration thereby partially to reduce the felting quality of the wool, but stopping the treatment before the wool has lost more than 20% of its initial tensile strength, neutralizing the wool with acid and washing it to remove the acid, and

wetting the wool with a water dispersion of an amino-aldehyde pre-condensate, the dispersion containing from 3 to 6% total solids together with a fractional percentage of an appropriate catalyst, and curing the wool at a temperature of approximately 290 for a period of approximately eight minutes.

11. That method of stabilizing wool with respect to laundry shrinkage which comprises as steps first treating the wool with an alcoholic solution containing 7.5% sodium hydroxide, the treatment lasting for approximately five minutes and being carried out at a temperature 01 70 F., removing surplus solution, neutralizing the alkali with dilutesulphuric acid, rinsing and drying the wool, then immersing the wool in an aqueous dispersion of a low molecular weight urea-formaldemg carried out at 70 F. for a period of five minutes, removing surplus alkali, neutralizing the wool, washing the wool and drying it, then wetting the wool with an aqueous dispersion of a methylated methylol melamine lire-condensate, the dispersion containing approximately 3% total solids with approximately 0.1% (ii-ammonium hydrogen phosphate as a catalyst, removing surplus solution, drying the. wool, and curing it for eight minutes at 290 F. 4

13. That a method of stabilizing wool with respect to laundry shrinkage which comprises as steps first treating the wool with an alcoholic solution containing from 4.0 to 7.5% potassium hydroxide by weight the treatment being carried out at approximately 10 F. for a period varying inversely with the strength of caustic solution and between five and ten minutes, neutralizing 30 the wool with acid, washing the wool to remove the acid, and wetting the wool with a water dispersion of methylated methylol-melamine precondensate, the dispersion containing approximately 3% total solids and approximately 0.1%

as diammonium hydrogen phosphate as a catalyst,

and thereafter curing the wool at a temperature of approximately 290 F. for a period oi. approximately eight minutes to complete the polymerization of the pre-condensate. Y

EDWARD C. PFEFFER, Js. WALTER KITAJ. 

